GEP Posted January 3 Report Share Posted January 3 I am currently searching for a new cone 6 glossy base, and came across this very simple recipe. 50 Frit 3134 30 EPK 20 Silica I am attracted to how simple it is. But is it too simple? I know that some Frits are considered almost complete glazes on their own. I need a glaze that will withstand daily use and dishwashers. Has anyone here tried a recipe like this, or have any other thoughts about something this simple? Quote Link to comment Share on other sites More sharing options...
davidh4976 Posted January 3 Report Share Posted January 3 The B2O3 in your recipe is about 3-to-4 times higher than the target that Matt Katz has tested for dishwasher resilience. His NCECA 2012 presentation showed his experiments with B2O3 levels for good dishwasher resilience. Your recipe gives about 0.63 B2O3. Matt says 0.15 is an optimal level. Here is a clear glaze that fits within his charts of good dishwasher resilience that we are using. It has a good 'clear' look and seems to work well with covering underglazes without causing running. It is not at Matt's optimal B2O3 level, but still in a good range from his experimental results. It has 0.32 B2O3. We haven't done the dishwasher test on this recipe, so it would be worth testing yourself. Matt's presentation: https://help.glazy.org/downloads/pdf/Katz-NCECA 2012-PDF.pdf Recipe for our "Clear 3195" silica 19.500 epk 3.800 whiting 8.200 minspar 200 38.500 ferro frit 3195 26.300 dolomite 3.700 Quote Link to comment Share on other sites More sharing options...
Dick White Posted January 3 Report Share Posted January 3 Mea, this is a interesting recipe that shows up in a variety of places. The version you have is very close to one that we have been using in the Audrey Moore/Wakefield (Ffx County Parks) studio since forever. That one is Gerstley 50, EPK 17.5, Silica 32.5 (our Gerstley vs. your 3134, about the same effect; your EPK and silica are reversed from ours). From a chemistry standpoint, the massive amount of Gerstley or 3134 generates so much boron that it could/should be a low-fire glaze - and indeed I have seen it in published collections of earthenware glazes. At the same time, the alumina and silica levels are quite high, and so the glaze is robust enough to survive at cone 6. With the demise of Gerstley, I am reformulating it to use 3134, and my revised recipe becomes similar to yours. Something to consider - 30 EPK is a lot to have in a recipe, and will cause issues with shrinkage and cracking (leading to crawling during the firing) so replace half of it with calcined EPK. It just so happens right now I have a test tile with my revised recipe soaking in vinegar, so I will come back in a day or so with the outcome of that. GEP and Rae Reich 2 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 4 Report Share Posted January 4 (edited) 1 hour ago, davidh4976 said: he B2O3 in your recipe is about 3-to-4 times higher than the target that Matt Katz has tested for dishwasher resilience. His NCECA 2012 presentation showed his experiments with B2O3 levels for good dishwasher resilience. Your recipe gives about 0.63 B2O3. Matt says 0.15 is an optimal level. Katz’ research with boron was about melting point. His research about durability was: is there a reasonable flux ratio and being outside this ratio ….. likely non durable. Boron glass / glazes can be very robust and properly formulated low fire cone 04 glazes have tested very durable. The published chart was for melting point and not necessarily durability. Article here: https://ceramicartsnetwork.org/docs/default-source/uploadedfiles/wp-content/uploads/2008/10/tf-boroninglazes-0912.pdf The first part of the presentation cited is about flux ratio and implied durability. “The graph on this page shows the amount of boron required at any temperature. The purple-blue areas are underfired, while the red/ orange areas are very glossy. The vertical axis is temperature in celsius and the horizontal axis is UMF boron additions to a standard glaze. By finding the desired temperature and determining the position on the oblique line, you can figure out the corresponding required UMF boron level at that temperature. This chart applies from cone 06 to cone 10. As a general rule, we define the required amount of boron as an additional 0.1 mole (via UMF) of boron for every 50°C below cone 10 (1305°C). Boron is an exceptionally good material for adding to glazes as it makes glasses at lower temperatures that are just as strong and resistant to wear and chemical leaching as the best cone 10 glazes.” Edited January 4 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
GEP Posted January 4 Author Report Share Posted January 4 2 hours ago, Dick White said: It just so happens right now I have a test tile with my revised recipe soaking in vinegar, so I will come back in a day or so with the outcome of that. Would love to hear how it did in your test! Pres 1 Quote Link to comment Share on other sites More sharing options...
davidh4976 Posted January 4 Report Share Posted January 4 (edited) 3 hours ago, Bill Kielb said: Katz’ research with boron was about melting point. His research about durability was: is there a reasonable flux ratio and being outside this ratio ….. likely non durable. Boron glass / glazes can be very robust and properly formulated low fire cone 04 glazes have tested very durable. The published chart was for melting point and not necessarily durability. Article here: https://ceramicartsnetwork.org/docs/default-source/uploadedfiles/wp-content/uploads/2008/10/tf-boroninglazes-0912.pdf The first part of the presentation cited is about flux ratio and implied durability. “The graph on this page shows the amount of boron required at any temperature. The purple-blue areas are underfired, while the red/ orange areas are very glossy. The vertical axis is temperature in celsius and the horizontal axis is UMF boron additions to a standard glaze. By finding the desired temperature and determining the position on the oblique line, you can figure out the corresponding required UMF boron level at that temperature. This chart applies from cone 06 to cone 10. As a general rule, we define the required amount of boron as an additional 0.1 mole (via UMF) of boron for every 50°C below cone 10 (1305°C). Boron is an exceptionally good material for adding to glazes as it makes glasses at lower temperatures that are just as strong and resistant to wear and chemical leaching as the best cone 10 glazes.” page 11 of his 2012 NCECA presentation shows dishwasher durability/degradation. (https://help.glazy.org/downloads/pdf/Katz-NCECA 2012-PDF.pdf) His ideal of 0.15 boron for cone 6 was reinforced in his 2016 NCECA paper. (https://wiki.glazy.org/uploads/short-url/p2WebBEmKFvfRp4jFhIziHfQSTA.pdf) Edited January 4 by davidh4976 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 4 Report Share Posted January 4 (edited) 1 hour ago, davidh4976 said: His ideal of 0.15 boron for cone 6 was reinforced in his 2016 NCECA paper. Yes, he found an ideal boron level at cone 6 but really read through the beginning part of your citation, first several pages all refer to flux ratio, graphs are about flux ratio and his examples provided within the course are about flux ratio . If you took the course and have the notes lookup a glaze he termed Gel-o where he said “ At this point, I don’t see a reason to take functional glazes past 0.35 R2O : O.65 RO”. I feel If you are dismissing the flux ratio as being a significant primary part.of that research you are missing a significant important point. The boron research was centered on how much to melt at what cone. He concludes with a broader range for cone six, but again the ideal flux ratio is first and foremost. Edited January 4 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
Min Posted January 4 Report Share Posted January 4 Like to see some data showing the correlation between high silica and/or alumina levels in relation to boron level and flux ratios also. @Dick White, are you running a soda ash / alkaline test also? I'ld be curious to see crazing stress tests done with this glaze too. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 4 Report Share Posted January 4 11 minutes ago, Min said: Like to see some data showing the correlation between high silica and/or alumina levels in relation to boron level and flux ratios also. I would agree, the more the merrier. Gloss meter readings were an interesting indicator and something easy to replicate. Not really indexed to a quantifiable amount of degradation though. Still it likely is indicative. Stull correlated silica and alumina to a fixed flux ratio, but yes in clay there are an infinite number of fired combinations to which research could be applied. Quote Link to comment Share on other sites More sharing options...
Dick White Posted January 4 Report Share Posted January 4 @Min et al, I just pulled the tile after 24 hours half submerged in 30%* cleaning vinegar. There is no change in gloss or color (we use this glaze with a bit of copper and some tin/zirco for a nice turquoise). I will go shopping to find some plain lye (Drano brand has other stuff in it) - when home-brew testing, I like to hit the sample tile with something stronger than kitchen cabinet chems (since I run my dishwasher so infrequently, it would be next year before I would complete the Katz-recommended 30 cycles...). *Grocery store vinegar is diluted to an acidity of 5% - sometimes. In recent years as manufacturers everywhere try to reduce costs by invisibly reducing quantity in the same package, some grocery vinegars are now 4%. That might not make any difference in your oil and vinegar salad dressing, but if you like to make your own pickles, you need to check the label and make sure you are getting a 5% vinegar. And there, I did it again, took the pottery discussion in another direction. Now we can share recipes for pickles... Bill Kielb, Rae Reich, GEP and 1 other 4 Quote Link to comment Share on other sites More sharing options...
Roberta12 Posted January 4 Report Share Posted January 4 What about this clear? Credit Naomi Clement Minspar 200 40.00 Gerstley Borate 35.00 Kentucky OM4 Ball clay 15.00 Silica 10.00 Quote Link to comment Share on other sites More sharing options...
davidh4976 Posted January 4 Report Share Posted January 4 10 hours ago, Bill Kielb said: Yes, he found an ideal boron level at cone 6 but really read through the beginning part of your citation, first several pages all refer to flux ratio, graphs are about flux ratio and his examples provided within the course are about flux ratio . If you took the course and have the notes lookup a glaze he termed Gel-o where he said “ At this point, I don’t see a reason to take functional glazes past 0.35 R2O : O.65 RO”. I feel If you are dismissing the flux ratio as being a significant primary part.of that research you are missing a significant important point. The boron research was centered on how much to melt at what cone. He concludes with a broader range for cone six, but again the ideal flux ratio is first and foremost. I think we are talking 'past each other'. I'm not dismissing flux ratio. As you say, Matt's research shows it to be important. But, it was not the problem with the original question/recipe that started this thread. The original question and recipe had a good flux ratio, so I did not comment on it. What the recipe does have is a high boron level. That is why I commented on the boron level and not the flux ratio. I think we are in agreement and just suffering from the back-and-forth inherent in using the internet. Kelly in AK and Min 2 Quote Link to comment Share on other sites More sharing options...
Harold Roberts Posted January 4 Report Share Posted January 4 I used to use Frit 3134 as a substitute for Gerstley Borate back in the 80's when there was a Gerstley Borate shortage. I found it flocked my glazes the same way Gerstley Borate did. I concluded that there must be enough free Boron because of the low Silica and Alumina content in the formula that it remained soluble. Boron is a glass former. Anyone who has thrown Borax on a raku pot and found it created a beautiful glassy glaze has seen it in action. Overtime the glaze will desolve in water alone. I have a potter friend who used a beautiful clear glaze she was given by a well known ceramist that had way to much boron in it and overtime her glazes deteriorated. To answer your question Frit 3134 is not a complete glaze. It is used as a flux and needs more silica otherwise the free Boron will soften the glaze. There are a lot of great cone 6 clear glazes out there and davidh4976 glaze is probably a good one. Frit 3195 is much closer to a complete glaze. GEP 1 Quote Link to comment Share on other sites More sharing options...
Min Posted January 4 Report Share Posted January 4 (edited) If in doubt pay the (approx) $35- and send it to get it lab tested. In this case we are talking mainly about the boron so choose that as the oxide to test for. As to how much boron, I would be looking at drinking water guidelines. One here, an oversupply of boron in drinking water can have a nasty side effect, especially for males. https://bsclab.com/pottery-testing Edited January 4 by Min Quote Link to comment Share on other sites More sharing options...
Dick White Posted January 4 Report Share Posted January 4 (edited) And back to arguing about the Katz documents - all those graphs are based on a flux ratio of 30:70 R20:RO. Stull ran his infamous chart on this flux ratio. There is wide agreement that this ratio is optimal. There is also modest agreement about silica and alumina molar limits of generally 2.5 to 5 for silica and .25 to .5 for alumina for mid fire with a Si:Al ratio of around 7 or 8 being a nice glossy glaze. There is less published documentation showing that when keeping the flux and Si:Al ratios constant, cone 10 melt occurs higher up the diagonal on the Stull chart and cone 04 melt occurs lower down the diagonal. There is also wide agreement that boron is helpful at mid-fire and necessary at low-fire, with the Katz diagram showing recommended molar levels across the range of temperatures. But when we mix all that together and do something different, we don't really have any guidance, so as @davidh4976 just said, we talk past each other. The recipe @GEP is asking about is completely outside of conventional limits . The flux ratio is 22:78 - Katz spoke of not going above 35:65, but nothing about going below, where this one is significantly below the gold standard. The Si:Al ratio is 7.8, nice for a glossy, but the molar levels of 4.1 and .52 are in the cone 10 range. The boron molar level is at .72, a bit high for cone 04 (i.e., off the Katz chart). So what we have is a high calcium semi-matte (based on the flux ratio) with cone 10 glass (based on the silica and alumina molar levels) and cone 08 boron molar levels that comes out a nice glossy cone 6. As @Bill Kielb said, "there are an infinite number of fired combinations to which research could be applied." Edited January 7 by Dick White GEP 1 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 4 Report Share Posted January 4 (edited) 2 hours ago, Dick White said: And back to arguing about the Katz documents Not arguing actually Whether in his class or reading that paper 14 of the 16 pages were devoted to flux ratio. I just don’t think his primary focus was testing durability and boron levels. The one graph we have in the paper shows reasonable minimal gloss degradation from about 0.15 to 0.2@ cone 6. The low point at 0.15 out to let’s say 0.2 With confidence. His demonstration that durability and temperature independence of flux ratios however was a notable central finding which likely gives greater confidence flux ratios can be a leading indicator of durability. Can there be excess boron - certainly, yes. If I take the original recipe at 0.63 boron and simply apply Katz’ boron melt chart and fire to cone 04 it becomes durable? This research to me was not to establish that. It might just be my reading of 14 of the 16 pages though. Edited January 4 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted January 4 Report Share Posted January 4 Simple frit and clay glazes are the best. It's an interesting question, what happens if you fire a durable cone 04 glaze to cone 6? Does it lose any durability and become high in boron? I don't think I am looking at the same graphs, cone 10 glaze flux ratio look good from 0.6:0.4 to 0.2:0.8 R2O: RO and he even says the cone 6 no boron graph might be an error in his testing so that could be a pretty flat loss off gloss across the board. I would say his research is unconvincing about flux ratios but pretty good on boron increasing gloss durability. Quote Link to comment Share on other sites More sharing options...
Dick White Posted January 4 Report Share Posted January 4 As I see it, there is a lot of good work establishing ground zero for the perfect glossy durable midfire glaze - flux ratio of 30:70, Si and Al molar within limits, Si:Al ratio around 7-8, boron molar within limits, etc. Yes, perfect, but boring glazes. Mayco Stroke and Coat, a solid performer from 06 to 6. In my glaze chem classes, I tell them to consider theoretical perfection, but also realize there is are a lot of more interesting effects to be found outside of ground zero. Some of it may not be durable, though some may be just fine, do your tests. I have to this point stayed away from subjective experience with this particular recipe, but one of the reasons it is so popular in my community studio is because of the interest it creates. When layered with certain others of the studio glazes, we put the Amaco drizzles to shame. It is a solid glaze by itself, or Amaco/Mayco Flux in the same bucket. Why? In my studies of glazes, it is the high boron in this one when layered with other lower boron (conventional theoretic levels) glazes. Higher boron levels create a borosilicate glass. Lower boron levels create an alumino-silica glass (not quite soda-lime bottle glass, but the chemistry is moving in that direction). Layered borosilicate glass and alumino-silica glass do not mix to a homogeneous blend, but rather they are immiscible and flow through each other in rivulets or create a faux-oilspot effect. Now I have the student's attention (and if they are not careful, a kiln shelf to clean). As DuPont said 90 years ago, better living through modern chemistry. GEP, Rae Reich, Kelly in AK and 1 other 4 Quote Link to comment Share on other sites More sharing options...
Min Posted January 4 Report Share Posted January 4 Katz himself might have thrown a wrench in the works in regards to his testing into flux ratios, also into further exploration into silica:alumina flux ratios. From his 2016 NCECA presentation taken from this pdf. Bill Kielb 1 Quote Link to comment Share on other sites More sharing options...
Min Posted January 4 Report Share Posted January 4 21 minutes ago, Dick White said: In my studies of glazes, it is the high boron in this one when layered with other lower boron (conventional theoretic levels) glazes. Higher boron levels create a borosilicate glass. Lower boron levels create an alumino-silica glass (not quite soda-lime bottle glass, but the chemistry is moving in that direction). Layered borosilicate glass and alumino-silica glass do not mix to a homogeneous blend, but rather they are immiscible and flow through each other in rivulets or create a faux-oilspot effect. Good example of how layering 2 dissimilar glazes can often result in very interesting glaze effects. Kelly in AK 1 Quote Link to comment Share on other sites More sharing options...
Kelly in AK Posted January 7 Report Share Posted January 7 On 1/4/2024 at 11:57 AM, High Bridge Pottery said: It's an interesting question, what happens if you fire a durable cone 04 glaze to cone 6? Does it lose any durability and become high in boron? I appreciate this question. As well as the notion that simple frit and clay glazes are best . In the 2016 paper, Matt refers back to the 2012 presentation, discussing results of 0.5 R20:0.5 RO samples in relation to boron. He concludes that paragraph with: “Thus the quality of glazes is not dependent on any specific temperature for durability. Chemistry is the only relevant factor.” Obviously, temperature does matter, if a glaze hasn’t melted it’s not complete. But once it has fully melted, why would a glaze that’s durable at cone 04 (say, 0.3 R2O:0.7 RO, 0.5 boron) be less durable if fired to cone 6? It might run all over, but that’s a different problem. High Bridge Pottery 1 Quote Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted January 7 Report Share Posted January 7 So I actually just did a round of simulated dishwasher/acid testing on the 50:30:20 base glaze, but with some tin, RIO and rutile added (the combo is really ugly, so I don’t recommend them). It did pass both tests. But the colourants may also play a part in the flux ratio, according to the Katz research. (I’m not willing to throw that out entirely. I think we just don’t know all the modifiers on it yet.) As far as practical applications, it does appear to behave well in the bucket, doesn’t run unduly, although keep an eye on the thickness. It does react with other glazes reasonably well. My version is pretty expensive because of the tin, but even just the base glaze is a steeper cost than the base glaze we’re using at the teaching studio I’m at now. It’s not out of control, but the base runs $7.25/KG (Canadian dollars) and with 4% tin it’s $12.05/kg. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 7 Report Share Posted January 7 (edited) 5 hours ago, Kelly in AK said: Obviously, temperature does matter, if a glaze hasn’t melted it’s not complete. But once it has fully melted, why would a glaze that’s durable at cone 04 (say, 0.3 R2O:0.7 RO, 0.5 boron) be less durable if fired to cone 6? It might run all over, but that’s a different problem. Sorry the reason I mentioned the firing to cone 6 making a cone 04 glaze less durable because it was a good example that durability and boron were not tested or at least meaningfully tested and meaningfully quantified. I also mentioned it because many 04 glazes will fire just fine to cone 6 - Stroke and coat and look alike glazes seem to fall in this category. The only point was, while excess boron is certainly a thing, we generally should not conclude the current research predicts durability, hence the example that using it to predict an 04 glaze durability fired higher seems to be at odds using it to strictly predict durability. I do not think that was the focus of the 2012 research. Instead we were given a reasonable amount of research that indicated flux ratio’s outside a reasonable range could indicate a lack of durability. Why design your glazes there? Maybe test durability of those glazes approaching less reasonable ratios with a heightened awareness of the potential to be less durable. The gloss test is a doable one and relatively repeatable (if you have a decent gloss meter and maintain uniform measurement protocols) but it is dimensionless really so as a practical indicator and even trend indicator, likely fine. It is dimensionless so maybe no direct predictable correlation to longevity of service. I think the flux ratio research has shown merit and potential to be reasonably useful as qualified above but Boron and durability has not necessarily been tested and quantified. So I believe appropriate to say, why waste the material it’s not necessary to use that much. I do not believe what was written in 2012 was intended as a durability study on Boron in glazes……… just an indication of where did they appear best to melt. Edited January 7 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted January 7 Report Share Posted January 7 I'm still not convinced there's much in the flux ratio or wide agreement that 0.3:0.7 is ideal. Stull doesn't really give a reason for choosing 0.3:0.7 in his paper and just seems to sit in the middle of Orton's limits. Even looking at borosilicate laboratory glass recipes which are pretty durable they have no RO fluxes at all in the glass. I would think if you smashed up glassware into a frit you could get a pretty durable glaze that's 1 RO:0 R2O and 10x the boron limit. Quote Link to comment Share on other sites More sharing options...
Bam2015 Posted January 7 Report Share Posted January 7 (edited) This post is truly mind boggling to me. I know that glaze chemistry is complex, but this thread now makes me question if I should just buy commercial clear glaze rather than make my own because I might be creating an end product that is neither durable nor safe over time. Maybe I have no business making my own glaze if the info in this thread is way over my head. Edited January 7 by Bam2015 Kelly in AK 1 Quote Link to comment Share on other sites More sharing options...
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